The present invention relates to an altitude information acquiring device and an altitude information acquiring system for acquiring altitude information.
In recent years, some electronic watches have various measurement sensors mounted thereon so as to display not only time information but also various pieces of information such as various measurement values and calculated values. Further, some electronic watches have radio receiving units to receive radio waves from positioning satellites such as GPS, acquire position information (GPS positioning) and display the position information.
Some electronic watches have one of these types of display functions which can acquire and display altitude data and store a history of altitude changes. Conventionally, such altitude information is acquired by direct acquiring of altitude data by way of GPS positioning, or by indirect acquiring of altitude data using a conversion table between an atmospheric pressure and an altitude set in advance for estimating an altitude based on an atmospheric pressure measurement value measured by a pressure sensor. These altitude acquiring methods include different error factors. Hence, for example, Japanese Patent Application Laid-Open (JP-A) No. 2000-283775 discloses a technique of reducing an error based on a result of comparison of values acquired by using both of the acquiring methods in combination.
Further, there is an electronic watch which can not only simply acquire an altitude value at a point of time of measurement, but also acquire a relative altitude change and altitude history information about a peak position. For example, JP-A No. 5-172569 discloses a technique for performing accumulative calculation of total rise altitudes and total fall altitudes from a predetermined timing, respectively, and displaying them.
Further, in recent years, there is a technique related to the present invention for exchanging information between a plurality of mobile terminals using Bluetooth communication (registered trademark: Bluetooth) as disclosed in, for example, JP-A No. 2009-118403.
However, when obtaining a change of an altitude based on a measurement of the atmospheric pressure, if a user is stopping, moving on a flat road or moving slowly, there is a problem that the change occurs in an opposite direction due to change in weather conditions. On the other hand, applying GPS positioning increases power consumption and it leads a small device such as an electronic wristwatch in particular to become larger.
The present invention provides an altitude information acquiring device and an altitude information acquiring system which can accurately acquire the orientation and the magnitude of movement in an altitude direction while suppressing power consumption.